This invention provides a barring-tool system improving safety, speed, and effectiveness of maintenance of large engines, generators, and turbines, by controlled bidirectional rotation and locking of crankshafts, and a method for maintenance of large engines, generators, and turbines using the barring-tool system.
Large engines, generators, and turbines, are used to generate mechanical force for industrial processes, to pump fluids, and to generate electricity. These large engines are variations of the steam engines of the Industrial Revolution, and are characterized by a rotating crankshaft and pistons or the equivalent, where the force upon the pistons is translated into rotation of the crankshaft. The crankshaft generally extends outside the engine housing in at least one direction. In the 360 degrees of rotation of the crankshaft, there is a nominal zero-degree position known as top dead center—historically a point from which the engine could not move on its own. Historically, when a steam engine was stuck at top dead center, the crankshaft would be rotated by the application of human force leveraged through an iron or steel bar which engaged the teeth of a ring gear surrounding a flywheel surrounding the crankshaft. That is the origin of the term “barring” for rotating the crankshaft of an engine when it is not running.
Barring remains very important today, even when the engines are able to start from top dead center, because of maintenance requirements of engines. For maintenance, repair, retrofitting, and inspection of large engines, the engine cannot be running—that would kill the people performing the maintenance. There has to be a way to rotate the crankshaft under outside, controllable power, because pistons and other parts must be moved into positions where they can be inspected and worked upon, and then after that other pistons and parts must be moved into position. Partly because of this requirement for barring, engines are generally equipped with a flywheel surrounding the exposed crankshaft, and with a ring gear surrounding the flywheel.
Manual barring is still performed. See FIG. 1. The procedure requires more than one person, not only to produce sufficient force, but also to look into the engine through various openings on various sides of the engine housing to determine the positions of various parts. There is a great danger that the instructions from a person having a body part placed inside the engine for inspection or maintenance will not be heard in a noisy engine room, and that the other persons will rotate the crankshaft and injure that person.
Another disadvantage of the present state of the art for barring of engines is that after a crankshaft is put into its proper place, any addition, removal, or adjustment of parts inside the engine might shift the balance and cause a spontaneous rotation of the crankshaft, which is a condition that is dangerous to the maintenance personnel, and might damage the engine itself.
For many decades, the state of the art for barring of engines has been a single hydraulic jack providing essentially upward pressure on a ring gear surrounding a flywheel surrounding a crankshaft. Among the disadvantages of such an arrangement is that the hydraulic jack can only rotate the crankshaft in one direction, the hydraulic jack cannot lock the crankshaft against spontaneous rotation, and more than one person is still required—one to operate the hydraulic jack, and others to look into the engine through various openings and relay instructions to the jack operator. The danger of injury to personnel and of losing the desired positioning is still present with hydraulic jacking.
Although the engines are large, they are subject to close tolerances. The upward force exerted by a hydraulic jack in the present state of the art can deflect or bend a crankshaft by a significant amount, skewing the measurements and affecting the performance of the engine.
The use of electrical switches, motors, and equipment in most engine rooms is limited to explosion-proof electrical devices, costing significantly more than standard electrical devices. The use of pneumatic and hydraulic controls and actuators in an engine-room environment can provide a safer, more cost-effective system than a purely electrical one.
There is a need for a barring tool system which can be operated by one person who is free to move around the engine during the barring process for the purposes of observation, which applies a rotational force rather than upward force in order to avoid deflection, which is capable of locking a ring-gear-flywheel-crankshaft unit in place in order to avoid spontaneous rotation, and which is explosion-proof for operation in an engine-room environment.
Various patents discuss the use of a toothed pinion that intermeshes with a ring gear so as to manipulate the ring gear. The toothed pinion is then mechanically or manually acted upon to provide rotation of the ring gear. Some of the devices teach the use of a gripper to fasten to the ring gear device to be turned, wherein the gripper is connected to a motor which would rotate the gripper and ring gear device. Many patents discuss a ring gear fastened to an outer race of a slew bearing that has an inner race that is fastened to the structure to rotate within the outer race driven by the second motor.
U.S. Pat. No. 7,624,654 issued Matthew Fleming et al on Dec. 1, 2009 for “Automated System and Method for Probe Measurements of Stack Gas Flow Properties” discloses an automated probe for obtaining data at various locations in a stack flow. The measured characteristics relate to such properties as a stack gas stream and flow velocity. A probe assembly is introduced into a stack through a test port and operated by an automated mechanism mounted on the test port to position a sensing tip at various locations within the gas stream at proper yaw angle. A support structure for the probe assembly comprises end walls that are joined through two rigid trusses disposed on opposite sides of the probe assembly. Extending between the end walls is a servo-motor-powered linear actuator having a traveling carrier to which a gripper assembly is attached. As actuator operates, it moves the carrier to impart travel to the support structure, which supports the probe assembly while allowing the probe assembly to translate on the framework along an axis but constraining the probe assembly from turning on the framework about the axis. With a gripper assembly gripping the probe assembly and another gripper assembly released, a linear actuator can move the first gripper assembly along the axis to translate the probe assembly on the framework. A motor is also mounted on the framework. The motor can turn a pinion that is in mesh with a toothed segment of a ring gear, which attaches to the stack port so that the motor can turn the framework and probe assembly together about the axis. The patent also discloses a ring gear fastened to an outer race of a slew bearing that has an inner race that is fastened to the structure to rotate within the outer race driven by the second motor. The gripper assembly may be mounted on a carrier of a linear actuator which contains and is operated by the first motor.
U.S. Pat. No. 6,802,207 issued to Yoshifumi Okuda and Yahiko Iwasaki on Oct. 12, 2004 for “Rotational Driving Apparatus for Testing Internal Combustion Engine” discloses a rotational driving apparatus for testing an internal combustion engine. The apparatus has a rotor that is rotated about a rotation axis of the ring gear, and a pivot portion supported in a support position with respect to the rotor. The support position is located away from a front end and a rear end of the pivot portion in the direction of the rotation axis of the ring gear. An engaging portion is provided at the front end of the pivot portion with respect to the ring gear. Consequently, when the rotor is rotated, a torque in the direction in which the engaging portion is caused to engage the ring gear is generated by a portion between the support position and the rear end of the pivot portion. This torque cancels out at least a portion of a torque generated at a portion on the front end side of the pivot portion. As a result, the control force that is required to displace the engaging portion is reduced, even if the rotor is rotated at high speeds. In one described embodiment, a link that is operatively connected to the pivot portion directly or indirectly is employed so as to manipulate the engaging portion between an engaged position in which it engages the ring gear and a non-engaged position. This link is also joined to a reciprocating member that is shifted in the direction of the rotation axis by an actuator. The angle that is formed between the link and the rotation axis is preferably large. Thus, the horizontal component of the total torque generated by the centrifugal force that acts on the pivot portion is reduced before being transmitted to the reciprocating member, and thus the effects, when running at high speeds, of the centrifugal force on the control force for engaging the engaging portion with the ring gear can be further reduced.
U.S. Pat. No. 6,405,585 issued to Staley J Hewitt on Jun. 18, 2002 for “Portable Flywheel Test Assembly” discloses a portable dynamometer for testing an engine having an output shaft. The tester comprises a table frame, a flywheel drive axle which is mounted to the table, a flywheel coaxially secured to the flywheel drive axle, an engine mounting pad assembly, and an endless loop means. The axle is drivingly connected with a sprocket hub assembly, on which the flywheel is mounted. A ring gear is mounted for rotation on the axle in spaced relation to the flywheel. The unit to be tested mounts on a mounting plate which can be secured to the top—or side of the table. An endless loop drive mechanism interconnects the axle and the engine being tested. A chain or belt drivingly connects a driven sprocket or pulley hub assembly with the unit to be tested. The sprocket or pulley hub assembly can be moved to various locations along the axle. The table can also be pivoted ninety degrees. These features allow the flywheel test assembly to easily adapt to and test units having either horizontal or vertical output shafts. The flywheel test assembly also utilizes an automotive-type starter system in which the starter motor engages a ring gear attached to the axle. Thus, when the starter motor turns the ring gear, the flywheel, the sprocket hub assembly, and therefore the engine are driven. The ring gear may have a plurality of teeth in which the starter has a selectively extensible output gear with a plurality of teeth for engaging the ring gear when operated. Another feature of the invention includes a brake mounted on the frame for decelerating the flywheel through contact with the flywheel such that the flywheel acts as a rotor for the brake. The brake may comprise a hydraulically operated caliper brake with a first brake pad for engaging the flywheel and a second brake pad for engaging the second side surface of the flywheel.
U.S. Pat. No. 8,317,490 issued to John B. Manning Nov. 27, 2012 for “Torque Drive Mechanism for Gas Compressor” discloses a method for limiting startup current drawn by an electric motor used for moving pressurized fluid through a supply conduit. The drive mechanism incorporates one or more air or gas engine starters to initiate rotation of a gas compressor and its associated driving electric motor. The system for compression of gas includes a single shaft electric motor with a single motor shaft, a compressor with a compressor shaft, a coupler with a first end coupled to the single motor shaft and a second end coupled to the compressor shaft, a gear coupled to the coupler, and at least one starter selectively detachably coupled to the gear. The gear may be coupled to the first end of the coupler and in another embodiment, to the second end of the coupler. In a certain embodiment, the gear may include a flywheel with teeth at a periphery of the flywheel. In certain embodiments, the gear may include a flywheel further including a plurality of sections, each coupled the coupler. Each section may include one or more removable sections having teeth-like elements. The flywheel may also include a dished section coupled to the coupler. In additional embodiments of the invention, the system may include a plurality of starters capable of being selectively detachably coupled to the gear. The system may also include a detector of a rotational speed, possibly optical or a magnetic, of the single motor shaft and a controller coupled to the detector of the rotational speed of the single motor shaft and to the switch. The method includes the steps of mounting a gear on the coupler and mounting a starter selectively engagably coupled to the gear. In some embodiments of the invention, the method may include operationally connecting a regulator to a switch and connecting the regulator to a source of pressurized fluid and to the starter. In other embodiments, the method may include a step of operationally connecting another regulator to the starter and connecting that regulator to a source of pressurized fluid and to the starter.
U.S. Pat. No. 7,849,734 issued to Hitoshi Moritani on Dec. 14, 2010 for “Test Equipment of Engine Motoring” discloses test equipment for an engine motor. The test equipment has a conveying mechanism to carry an engine in and out of test position, a fixing mechanism to fix the engine, a coupling mechanism to directly couple an electrical motor to a crank shaft of the engine, an encoder to synchronize the electrical motor rotation, a plurality of detection units, a control means for controlling the movement of the positioning equipment, testing means, and a base that holds the electrical motor and coupling mechanism as well as supporting the conveying mechanism. The base has a frame formed in a gate shape and opens in the conveying direction to cover the sides and top of the engine while it is in the test position. The base also supports a plurality of detection and testing units about the frame. The coupling mechanism has a plurality of coupling fingers that are swingably driven to engage with the ring gear. The coupling mechanism is placed behind the engine and is fixed to the base via a holder. The coupling mechanism has a transmitting member that transmits the rotation of the electric motor turning the motor as the electric motor rotates.
U.S. Pat. No. 4,535,655 issued Robert C. Avery Aug. 20, 1985 for “Engine Turning Tool Bracket” discloses an apparatus useful for manually rotating a rotable system, such as an engine. The apparatus has a stationary housing with an opening, a plate with slots, a bar with capability of being placed between the slots contacting the engine and rotating the engine manually by way of the bar. The plate is removably secured or fastened by means of bolting the plate to the housing and may be adjustable. The bar can be placed at least partially in the slot so that the first end contacts the system and the second end is capable of being manually held. With the bar in this position, manually rotating the bar, e.g., about the slot in which the bar placed, causes the system to rotate as desired. The disclosure contemplates that the apparatus may be used to work on an engine, transmission, clutch, or similar rotatable mechanism.
U.S. Pat. No. 5,018,414 issued Richard Naumann May 28, 1991 for “Transmission Servicing Tool” discloses a tool to facilitate removal and servicing an automotive transmission wherein the transmission comprises a housing operatively mounted on an engine, a wheel rotatably mounted in the housing, and a ring gear on the wheel being engaged by the pinion of a starter motor. The torque converter repair tool has a small plate that can be mounted on the torque converter housing with the starter motor removed. A positioning hole in the plate engages over a locator stud, which is normally used to position the starter motor, and another hole slidably receives a hand screw that threads into a tapped hole in the housing to secure the tool temporarily in place. A shaft is rotatable in the plate, and, when in place, a pinion on the inboard portion of the shaft engages the ring gear of the torque converter. The outboard end of the shaft may be engaged by a socket wrench for hand rotation of the shaft and, with it, the flywheel.
U.S. Pat. No. 4,979,409 issued Junior G Garrett and Robert L. Meadows Dec. 25, 1990 for “Clutch Adjusting Tool” discloses an adjusting tool for adjusting the ring of a clutch assembly by which the tool grips the clutch ring gear and allows for manual manipulation of the ring gear. The tool has a mounting fixture for attachment to the housing with a drive gear device which engage the lugs and thereby engage the ring gear, a drive gear shaft with gear teeth to mesh with the lugs on the ring gear, and a mounting fixture with an opening for rotatably supporting the driver gear shaft. The ring gear can be engaged with the tool through the use of a suitable wrench. In another embodiment the mounting fixture has a base and threadably attached to an adjusting ring rotated about an axis to move the ring. Other features include three gear teeth radiating from the shaft. In another embodiment the cover has an access hole cover attachment that allows reasonable means of mounting the tool to the cover.